X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fptrace.c;h=dfcd83ceee3b246326cbec2a6eadb27abdba7823;hb=c8a250058656495be02c00de61e26b017c86ef00;hp=973d727f5e846621c43e471d71b08364b9d04aeb;hpb=5b88abbf770a0e1975c668743100f42934f385e8;p=safe%2Fjmp%2Flinux-2.6

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 973d727..dfcd83c 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -20,9 +20,19 @@
 #include <linux/signal.h>
 #include <linux/audit.h>
 #include <linux/pid_namespace.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
 
-#include <asm/pgtable.h>
-#include <asm/uaccess.h>
+
+/*
+ * Initialize a new task whose father had been ptraced.
+ *
+ * Called from copy_process().
+ */
+void ptrace_fork(struct task_struct *child, unsigned long clone_flags)
+{
+	arch_ptrace_fork(child, clone_flags);
+}
 
 /*
  * ptrace a task: make the debugger its new parent and
@@ -32,15 +42,11 @@
  */
 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
 {
-	BUG_ON(!list_empty(&child->ptrace_list));
-	if (child->parent == new_parent)
-		return;
-	list_add(&child->ptrace_list, &child->parent->ptrace_children);
-	remove_parent(child);
+	BUG_ON(!list_empty(&child->ptrace_entry));
+	list_add(&child->ptrace_entry, &new_parent->ptraced);
 	child->parent = new_parent;
-	add_parent(child);
 }
- 
+
 /*
  * Turn a tracing stop into a normal stop now, since with no tracer there
  * would be no way to wake it up with SIGCONT or SIGKILL.  If there was a
@@ -48,15 +54,19 @@ void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
  * TASK_TRACED, resume it now.
  * Requires that irqs be disabled.
  */
-void ptrace_untrace(struct task_struct *child)
+static void ptrace_untrace(struct task_struct *child)
 {
 	spin_lock(&child->sighand->siglock);
-	if (child->state == TASK_TRACED) {
-		if (child->signal->flags & SIGNAL_STOP_STOPPED) {
-			child->state = TASK_STOPPED;
-		} else {
+	if (task_is_traced(child)) {
+		/*
+		 * If the group stop is completed or in progress,
+		 * this thread was already counted as stopped.
+		 */
+		if (child->signal->flags & SIGNAL_STOP_STOPPED ||
+		    child->signal->group_stop_count)
+			__set_task_state(child, TASK_STOPPED);
+		else
 			signal_wake_up(child, 1);
-		}
 	}
 	spin_unlock(&child->sighand->siglock);
 }
@@ -72,14 +82,11 @@ void __ptrace_unlink(struct task_struct *child)
 	BUG_ON(!child->ptrace);
 
 	child->ptrace = 0;
-	if (!list_empty(&child->ptrace_list)) {
-		list_del_init(&child->ptrace_list);
-		remove_parent(child);
-		child->parent = child->real_parent;
-		add_parent(child);
-	}
+	child->parent = child->real_parent;
+	list_del_init(&child->ptrace_entry);
 
-	if (child->state == TASK_TRACED)
+	arch_ptrace_untrace(child);
+	if (task_is_traced(child))
 		ptrace_untrace(child);
 }
 
@@ -98,30 +105,32 @@ int ptrace_check_attach(struct task_struct *child, int kill)
 	 * be changed by us so it's not changing right after this.
 	 */
 	read_lock(&tasklist_lock);
-	if ((child->ptrace & PT_PTRACED) && child->parent == current &&
-	    (!(child->ptrace & PT_ATTACHED) || child->real_parent != current)
-	    && child->signal != NULL) {
+	if ((child->ptrace & PT_PTRACED) && child->parent == current) {
 		ret = 0;
+		/*
+		 * child->sighand can't be NULL, release_task()
+		 * does ptrace_unlink() before __exit_signal().
+		 */
 		spin_lock_irq(&child->sighand->siglock);
-		if (child->state == TASK_STOPPED) {
+		if (task_is_stopped(child))
 			child->state = TASK_TRACED;
-		} else if (child->state != TASK_TRACED && !kill) {
+		else if (!task_is_traced(child) && !kill)
 			ret = -ESRCH;
-		}
 		spin_unlock_irq(&child->sighand->siglock);
 	}
 	read_unlock(&tasklist_lock);
 
-	if (!ret && !kill) {
-		wait_task_inactive(child);
-	}
+	if (!ret && !kill)
+		ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
 
 	/* All systems go.. */
 	return ret;
 }
 
-int __ptrace_may_attach(struct task_struct *task)
+int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
+	const struct cred *cred = current_cred(), *tcred;
+
 	/* May we inspect the given task?
 	 * This check is used both for attaching with ptrace
 	 * and for allowing access to sensitive information in /proc.
@@ -134,27 +143,33 @@ int __ptrace_may_attach(struct task_struct *task)
 	/* Don't let security modules deny introspection */
 	if (task == current)
 		return 0;
-	if (((current->uid != task->euid) ||
-	     (current->uid != task->suid) ||
-	     (current->uid != task->uid) ||
-	     (current->gid != task->egid) ||
-	     (current->gid != task->sgid) ||
-	     (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
+	rcu_read_lock();
+	tcred = __task_cred(task);
+	if ((cred->uid != tcred->euid ||
+	     cred->uid != tcred->suid ||
+	     cred->uid != tcred->uid  ||
+	     cred->gid != tcred->egid ||
+	     cred->gid != tcred->sgid ||
+	     cred->gid != tcred->gid) &&
+	    !capable(CAP_SYS_PTRACE)) {
+		rcu_read_unlock();
 		return -EPERM;
+	}
+	rcu_read_unlock();
 	smp_rmb();
 	if (task->mm)
 		dumpable = get_dumpable(task->mm);
 	if (!dumpable && !capable(CAP_SYS_PTRACE))
 		return -EPERM;
 
-	return security_ptrace(current, task);
+	return security_ptrace_may_access(task, mode);
 }
 
-int ptrace_may_attach(struct task_struct *task)
+bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
 	int err;
 	task_lock(task);
-	err = __ptrace_may_attach(task);
+	err = __ptrace_may_access(task, mode);
 	task_unlock(task);
 	return !err;
 }
@@ -167,11 +182,17 @@ int ptrace_attach(struct task_struct *task)
 	audit_ptrace(task);
 
 	retval = -EPERM;
-	if (task->pid <= 1)
-		goto out;
 	if (same_thread_group(task, current))
 		goto out;
 
+	/* Protect exec's credential calculations against our interference;
+	 * SUID, SGID and LSM creds get determined differently under ptrace.
+	 */
+	retval = mutex_lock_interruptible(&current->cred_exec_mutex);
+	if (retval  < 0)
+		goto out;
+
+	retval = -EPERM;
 repeat:
 	/*
 	 * Nasty, nasty.
@@ -196,39 +217,78 @@ repeat:
 	/* the same process cannot be attached many times */
 	if (task->ptrace & PT_PTRACED)
 		goto bad;
-	retval = __ptrace_may_attach(task);
+	retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
 	if (retval)
 		goto bad;
 
 	/* Go */
-	task->ptrace |= PT_PTRACED | ((task->real_parent != current)
-				      ? PT_ATTACHED : 0);
+	task->ptrace |= PT_PTRACED;
 	if (capable(CAP_SYS_PTRACE))
 		task->ptrace |= PT_PTRACE_CAP;
 
 	__ptrace_link(task, current);
 
-	force_sig_specific(SIGSTOP, task);
-
+	send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 bad:
 	write_unlock_irqrestore(&tasklist_lock, flags);
 	task_unlock(task);
+	mutex_unlock(&current->cred_exec_mutex);
 out:
 	return retval;
 }
 
-static inline void __ptrace_detach(struct task_struct *child, unsigned int data)
+/*
+ * Called with irqs disabled, returns true if childs should reap themselves.
+ */
+static int ignoring_children(struct sighand_struct *sigh)
 {
-	child->exit_code = data;
-	/* .. re-parent .. */
-	__ptrace_unlink(child);
-	/* .. and wake it up. */
-	if (child->exit_state != EXIT_ZOMBIE)
-		wake_up_process(child);
+	int ret;
+	spin_lock(&sigh->siglock);
+	ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
+	      (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
+	spin_unlock(&sigh->siglock);
+	return ret;
+}
+
+/*
+ * Called with tasklist_lock held for writing.
+ * Unlink a traced task, and clean it up if it was a traced zombie.
+ * Return true if it needs to be reaped with release_task().
+ * (We can't call release_task() here because we already hold tasklist_lock.)
+ *
+ * If it's a zombie, our attachedness prevented normal parent notification
+ * or self-reaping.  Do notification now if it would have happened earlier.
+ * If it should reap itself, return true.
+ *
+ * If it's our own child, there is no notification to do.
+ * But if our normal children self-reap, then this child
+ * was prevented by ptrace and we must reap it now.
+ */
+static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
+{
+	__ptrace_unlink(p);
+
+	if (p->exit_state == EXIT_ZOMBIE) {
+		if (!task_detached(p) && thread_group_empty(p)) {
+			if (!same_thread_group(p->real_parent, tracer))
+				do_notify_parent(p, p->exit_signal);
+			else if (ignoring_children(tracer->sighand))
+				p->exit_signal = -1;
+		}
+		if (task_detached(p)) {
+			/* Mark it as in the process of being reaped. */
+			p->exit_state = EXIT_DEAD;
+			return true;
+		}
+	}
+
+	return false;
 }
 
 int ptrace_detach(struct task_struct *child, unsigned int data)
 {
+	bool dead = false;
+
 	if (!valid_signal(data))
 		return -EIO;
 
@@ -237,14 +297,45 @@ int ptrace_detach(struct task_struct *child, unsigned int data)
 	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 
 	write_lock_irq(&tasklist_lock);
-	/* protect against de_thread()->release_task() */
-	if (child->ptrace)
-		__ptrace_detach(child, data);
+	/*
+	 * This child can be already killed. Make sure de_thread() or
+	 * our sub-thread doing do_wait() didn't do release_task() yet.
+	 */
+	if (child->ptrace) {
+		child->exit_code = data;
+		dead = __ptrace_detach(current, child);
+	}
 	write_unlock_irq(&tasklist_lock);
 
+	if (unlikely(dead))
+		release_task(child);
+
 	return 0;
 }
 
+/*
+ * Detach all tasks we were using ptrace on.
+ */
+void exit_ptrace(struct task_struct *tracer)
+{
+	struct task_struct *p, *n;
+	LIST_HEAD(ptrace_dead);
+
+	write_lock_irq(&tasklist_lock);
+	list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
+		if (__ptrace_detach(tracer, p))
+			list_add(&p->ptrace_entry, &ptrace_dead);
+	}
+	write_unlock_irq(&tasklist_lock);
+
+	BUG_ON(!list_empty(&tracer->ptraced));
+
+	list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
+		list_del_init(&p->ptrace_entry);
+		release_task(p);
+	}
+}
+
 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 {
 	int copied = 0;
@@ -265,7 +356,7 @@ int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst
 		copied += retval;
 		src += retval;
 		dst += retval;
-		len -= retval;			
+		len -= retval;
 	}
 	return copied;
 }
@@ -290,7 +381,7 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds
 		copied += retval;
 		src += retval;
 		dst += retval;
-		len -= retval;			
+		len -= retval;
 	}
 	return copied;
 }
@@ -323,9 +414,8 @@ static int ptrace_setoptions(struct task_struct *child, long data)
 	return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
 }
 
-static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data)
+static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 {
-	siginfo_t lastinfo;
 	int error = -ESRCH;
 
 	read_lock(&tasklist_lock);
@@ -333,31 +423,25 @@ static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data)
 		error = -EINVAL;
 		spin_lock_irq(&child->sighand->siglock);
 		if (likely(child->last_siginfo != NULL)) {
-			lastinfo = *child->last_siginfo;
+			*info = *child->last_siginfo;
 			error = 0;
 		}
 		spin_unlock_irq(&child->sighand->siglock);
 	}
 	read_unlock(&tasklist_lock);
-	if (!error)
-		return copy_siginfo_to_user(data, &lastinfo);
 	return error;
 }
 
-static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data)
+static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 {
-	siginfo_t newinfo;
 	int error = -ESRCH;
 
-	if (copy_from_user(&newinfo, data, sizeof (siginfo_t)))
-		return -EFAULT;
-
 	read_lock(&tasklist_lock);
 	if (likely(child->sighand != NULL)) {
 		error = -EINVAL;
 		spin_lock_irq(&child->sighand->siglock);
 		if (likely(child->last_siginfo != NULL)) {
-			*child->last_siginfo = newinfo;
+			*child->last_siginfo = *info;
 			error = 0;
 		}
 		spin_unlock_irq(&child->sighand->siglock);
@@ -410,9 +494,9 @@ static int ptrace_resume(struct task_struct *child, long request, long data)
 		if (unlikely(!arch_has_single_step()))
 			return -EIO;
 		user_enable_single_step(child);
-	}
-	else
+	} else {
 		user_disable_single_step(child);
+	}
 
 	child->exit_code = data;
 	wake_up_process(child);
@@ -424,8 +508,16 @@ int ptrace_request(struct task_struct *child, long request,
 		   long addr, long data)
 {
 	int ret = -EIO;
+	siginfo_t siginfo;
 
 	switch (request) {
+	case PTRACE_PEEKTEXT:
+	case PTRACE_PEEKDATA:
+		return generic_ptrace_peekdata(child, addr, data);
+	case PTRACE_POKETEXT:
+	case PTRACE_POKEDATA:
+		return generic_ptrace_pokedata(child, addr, data);
+
 #ifdef PTRACE_OLDSETOPTIONS
 	case PTRACE_OLDSETOPTIONS:
 #endif
@@ -435,12 +527,22 @@ int ptrace_request(struct task_struct *child, long request,
 	case PTRACE_GETEVENTMSG:
 		ret = put_user(child->ptrace_message, (unsigned long __user *) data);
 		break;
+
 	case PTRACE_GETSIGINFO:
-		ret = ptrace_getsiginfo(child, (siginfo_t __user *) data);
+		ret = ptrace_getsiginfo(child, &siginfo);
+		if (!ret)
+			ret = copy_siginfo_to_user((siginfo_t __user *) data,
+						   &siginfo);
 		break;
+
 	case PTRACE_SETSIGINFO:
-		ret = ptrace_setsiginfo(child, (siginfo_t __user *) data);
+		if (copy_from_user(&siginfo, (siginfo_t __user *) data,
+				   sizeof siginfo))
+			ret = -EFAULT;
+		else
+			ret = ptrace_setsiginfo(child, &siginfo);
 		break;
+
 	case PTRACE_DETACH:	 /* detach a process that was attached. */
 		ret = ptrace_detach(child, data);
 		break;
@@ -484,14 +586,34 @@ int ptrace_traceme(void)
 	/*
 	 * Are we already being traced?
 	 */
+repeat:
 	task_lock(current);
 	if (!(current->ptrace & PT_PTRACED)) {
-		ret = security_ptrace(current->parent, current);
 		/*
-		 * Set the ptrace bit in the process ptrace flags.
+		 * See ptrace_attach() comments about the locking here.
 		 */
-		if (!ret)
+		unsigned long flags;
+		if (!write_trylock_irqsave(&tasklist_lock, flags)) {
+			task_unlock(current);
+			do {
+				cpu_relax();
+			} while (!write_can_lock(&tasklist_lock));
+			goto repeat;
+		}
+
+		ret = security_ptrace_traceme(current->parent);
+
+		/*
+		 * Check PF_EXITING to ensure ->real_parent has not passed
+		 * exit_ptrace(). Otherwise we don't report the error but
+		 * pretend ->real_parent untraces us right after return.
+		 */
+		if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 			current->ptrace |= PT_PTRACED;
+			__ptrace_link(current, current->real_parent);
+		}
+
+		write_unlock_irqrestore(&tasklist_lock, flags);
 	}
 	task_unlock(current);
 	return ret;
@@ -511,12 +633,6 @@ struct task_struct *ptrace_get_task_struct(pid_t pid)
 {
 	struct task_struct *child;
 
-	/*
-	 * Tracing init is not allowed.
-	 */
-	if (pid == 1)
-		return ERR_PTR(-EPERM);
-
 	read_lock(&tasklist_lock);
 	child = find_task_by_vpid(pid);
 	if (child)
@@ -532,8 +648,7 @@ struct task_struct *ptrace_get_task_struct(pid_t pid)
 #define arch_ptrace_attach(child)	do { } while (0)
 #endif
 
-#ifndef __ARCH_SYS_PTRACE
-asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
+SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
 {
 	struct task_struct *child;
 	long ret;
@@ -571,8 +686,6 @@ asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
 		goto out_put_task_struct;
 
 	ret = arch_ptrace(child, request, addr, data);
-	if (ret < 0)
-		goto out_put_task_struct;
 
  out_put_task_struct:
 	put_task_struct(child);
@@ -580,7 +693,6 @@ asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
 	unlock_kernel();
 	return ret;
 }
-#endif /* __ARCH_SYS_PTRACE */
 
 int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data)
 {
@@ -600,3 +712,102 @@ int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data)
 	copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
 	return (copied == sizeof(data)) ? 0 : -EIO;
 }
+
+#if defined CONFIG_COMPAT
+#include <linux/compat.h>
+
+int compat_ptrace_request(struct task_struct *child, compat_long_t request,
+			  compat_ulong_t addr, compat_ulong_t data)
+{
+	compat_ulong_t __user *datap = compat_ptr(data);
+	compat_ulong_t word;
+	siginfo_t siginfo;
+	int ret;
+
+	switch (request) {
+	case PTRACE_PEEKTEXT:
+	case PTRACE_PEEKDATA:
+		ret = access_process_vm(child, addr, &word, sizeof(word), 0);
+		if (ret != sizeof(word))
+			ret = -EIO;
+		else
+			ret = put_user(word, datap);
+		break;
+
+	case PTRACE_POKETEXT:
+	case PTRACE_POKEDATA:
+		ret = access_process_vm(child, addr, &data, sizeof(data), 1);
+		ret = (ret != sizeof(data) ? -EIO : 0);
+		break;
+
+	case PTRACE_GETEVENTMSG:
+		ret = put_user((compat_ulong_t) child->ptrace_message, datap);
+		break;
+
+	case PTRACE_GETSIGINFO:
+		ret = ptrace_getsiginfo(child, &siginfo);
+		if (!ret)
+			ret = copy_siginfo_to_user32(
+				(struct compat_siginfo __user *) datap,
+				&siginfo);
+		break;
+
+	case PTRACE_SETSIGINFO:
+		memset(&siginfo, 0, sizeof siginfo);
+		if (copy_siginfo_from_user32(
+			    &siginfo, (struct compat_siginfo __user *) datap))
+			ret = -EFAULT;
+		else
+			ret = ptrace_setsiginfo(child, &siginfo);
+		break;
+
+	default:
+		ret = ptrace_request(child, request, addr, data);
+	}
+
+	return ret;
+}
+
+asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
+				  compat_long_t addr, compat_long_t data)
+{
+	struct task_struct *child;
+	long ret;
+
+	/*
+	 * This lock_kernel fixes a subtle race with suid exec
+	 */
+	lock_kernel();
+	if (request == PTRACE_TRACEME) {
+		ret = ptrace_traceme();
+		goto out;
+	}
+
+	child = ptrace_get_task_struct(pid);
+	if (IS_ERR(child)) {
+		ret = PTR_ERR(child);
+		goto out;
+	}
+
+	if (request == PTRACE_ATTACH) {
+		ret = ptrace_attach(child);
+		/*
+		 * Some architectures need to do book-keeping after
+		 * a ptrace attach.
+		 */
+		if (!ret)
+			arch_ptrace_attach(child);
+		goto out_put_task_struct;
+	}
+
+	ret = ptrace_check_attach(child, request == PTRACE_KILL);
+	if (!ret)
+		ret = compat_arch_ptrace(child, request, addr, data);
+
+ out_put_task_struct:
+	put_task_struct(child);
+ out:
+	unlock_kernel();
+	return ret;
+}
+#endif	/* CONFIG_COMPAT */